So my A4 is being a real PITA lately......I'm not able to connect to it with my vag com. I replaced the ecu as I couldn't conect at all, and the car ran like hell. Well the car runs well now (still no boost if you read my previous post), but I still cannot scan the codes with a vag com.....
Anyone have any suggestions where to go?

Fues are good

ECU is not fried (known good one swapped in)

Sometimes you plug the cable in, it goes green, and you can start to pull codes for a second, then it loses it and begins blinking red?

syonarag60style

06-05-2008, 05:31 AM

no one?

Nebone

06-05-2008, 05:34 AM

Check the OBD-2 connector under the steering wheel. Lower your dash (like 4 screws) and you'll be able to pull the plug out. Then connect the plug directly into the VAG cable to see if it makes a difference.

Militant-Grunt

06-05-2008, 10:00 AM

Is your ABS functional / you have a abs light on / flashing brake light?

If you do disconnect the ABS, then try connecting.

Nebone

06-05-2008, 10:06 AM

Is your ABS functional / you have a abs light on / flashing brake light?

If you do disconnect the ABS, then try connecting.

That shouldn't matter!? I worked on a 98 B5 with bad ABS and brake light on and computer connected just fine.

same with ABS. ABS is fine, but I disconnected it anyways just in case and it was still no better

audinutt

06-05-2008, 05:01 PM

how about an aftermarket radio does it have one??

-richard

syonarag60style

06-05-2008, 05:05 PM

Nope, OE radio...doesn't work, but its not aftermarket

Militant-Grunt

06-05-2008, 05:27 PM

That shouldn't matter!? I worked on a 98 B5 with bad ABS and brake light on and computer connected just fine.

It matters, just because you had the abs light on doesn't mean your abs module was bad, could've had a bad abs sensor. Vag com will not connect to the ecu if the abs module is bad.

syonarag60style

06-05-2008, 05:57 PM

It matters, just because you had the abs light on doesn't mean your abs module was bad, could've had a bad abs sensor. Vag com will not connect to the ecu if the abs module is bad.

Correct[up]

MattzWarsteiner

06-05-2008, 09:35 PM

Vag com will not connect to the ecu if the abs module is bad.

Or any other module from what I understand about VAG data systems. All modules share the same data bus with the OBD connector. If any one module is spewing noise or won't relinquish control of the bus, nobody can talk.

Pulling fuses module by module may narrow it down but you might have to disconnect them to find the offending data box. Go with the A4 experts and pull the ABS box first.

If this doesn't get things talking again, you might want to plug your cable into another car to see if it works before spending too much time troubleshooting the car side of things, right.

Or any other module from what I understand about VAG data systems. All modules share the same data bus with the OBD connector. If any one module is spewing noise or won't relinquish control of the bus, nobody can talk.

Pulling fuses module by module may narrow it down but you might have to disconnect them to find the offending data box. Go with the A4 experts and pull the ABS box first.

If this doesn't get things talking again, you might want to plug your cable into another car to see if it works before spending too much time troubleshooting the car side of things, right.